numbers - Do we have to use ordinals with largest/smallest?

In every-day language, I would say, "Give me the fifth largest pumpkin you have"; that is I would use the ordinal.

However, this feels clunky in mathematical texts, especially when reading out loud: "select the k-th largest element" or, even worse, "the k plus first/oneth largest element".

Is it fair to say/write "the k-largest element"? It seems to me that the "aspect of ordinality" is sufficiently expressed by the -st suffix in larger (or smallest, heaviest, ...), that is the superlative.